Steam generator



March 6, 1928.

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March 6, `1928.

H. A. NICHOLSON STEAM GENERATO Filed March4 24. 1919 March 6, 1928.

' H. A. N1cHo| soN- STEAM GNRATR 1f is? Zar March 6, 19.28.

'H. A. NICHOLSON STEAMYGENERATOR Filed March 24; 1919 sheets-she "D u A Invefz'or mmf March s, 192s. Y

H. A. Mci-:OLSON vsx'EA'M GENERATOR Filed garen 24, `119- 6 Sheets-Sheet, 5

I I March 6, 1928.

A. NICHOLSON STEAM GENERATOR 6 Sheets-Sheet 6 Fild March` 24. 1919 Patentes Mar. s, i928.

@UNITED A STATES .PATENT OFFICE. I

HENRY A. NICHOLSON, F ARKLES BAY, yAUCKLAND, NEW ZEALAND, ASSIGNOR T0 I ERNEST A.. CRAIG, OF AUCKLAND, NEW ZEALAND.

STEAM GENERATOR.

Application led March 24, 1919. Serial No. 284,657.

This invention relates to means for nerating steam for factory, transportation, electrical and other general uses, with a view to economy of fuel, Water,space, and cost of manufacture, installation and upkeep, and increase in efficiency of the apparatus and rapidity of steam generation. f

The water is pumped into'one end vof a system of piping, through which the pump l0 forces the fluid until it is'delivered from the other end of the piping system in the' form of steam at the required pressure.. The .fluid flows constantly .through the system, and heat is supplied at every stage until the teml5 pera'ture of the fluid far exceeds `212" 4F.

oreover, the time taken for the ,fluid to progress from the intake to the delivery end of the system is only lon enough to enable it to acquire Vthe desired egree of heat once.

' 20 In other words, each portion of fluidv remains Within the generator only a sufficient length of time to bring it but once to the required heat. In the present generator, it is not the bulk that is depended upon for ca pacity in generating steam, but rather the activity of thepump which forces the fluid through .the generator'fast enough to deliver the full amount of steam required. Thus, the generator vmay be composed of small and easily handled parts, and may be of small bulk, effecting a great saving in radiation of heat as well as space, initial cost, expense of installing, liability to injury, and cost of cleaning and repairs. Heretofore, the aim of boiler designers has been to provide a large heating surface, and perfect circulation of Water. The present generator has a relatively small heating surface and no circulation of water. The smallness of the heating surface is rendered possible by thefact that the Water does not circulate, but is heated only once and as soon as heated is used. The water is primarily heated and stored in a reservoir, from Whichit is taken and divided between two headers, Where the water stream is still `further split up into small streams, which are further heated by successive applications of heat at successive 5o portions of then' fiow, the streams being again collected and delivered to another drum, into which the highly heated fluid isdelivered. The fluid flows continuously. in one direction through the primary main and throughout the, generator. There is no circueinploy a. gas-producer,

eration. It will be understood that the heat of the fluid may be augmented at every portion of its progress, and that the final or highest heat may be imparted to it just as it is about to reach a place Where it can expand into steam so that there is no more heating than is absolutely necessary in order to produce steam at the consumption rate thereof, leading to the aforesaid economy in fuel, as Well as in the Weightv of water contained at any time in the apparatus, Awhich accordingly may be of diminutive bulk and weight in view of theV quantity4 of steam generated, with corresponding saving in room, and in cost of manufacture, transpoi-tation and upkeep.

Since a pound of fneLn burning into carbon monoxide may develop 8900 heat units, and since also by Vburning the-carbon monoxide into carbon dioxide 10,150 additional heat units may be developed, it is a further object of the present invention to utilize as far as possible the @undeveloped at both of these stagesg'a'n'd hence this feature of the invention relates-.to' the preferred eneral structure of the apparatus. I pre erably in whose walls is embedded that initialor large diameter portion of the pipe systmfthroughwhich the water may flow atrelatively slow speed to receive its initial heating. n this gas-producer sufficient air issupplied to produce carbon monoxide by the combustion of the fuel, the carbon monoxide, which is maintained at ignition temperature, being thereupon given a fresh supply of preferably, heated air, and led into a flame chamber through which flow the thin streams intol y which the waterhas been divided as al- 95 ready explained. In this chamber, which may be regarded as forming the secondary portion of a regenerative furnace, the flames are caused to take a. tortuous course, to enable the fine streams to abstract the utmost 1o. heat from the flames. The direction-0f flow is suchthat as the streams are about to emerge from this chamber, they are subject'- ed to the most intense heat from the flames. I believe it is novel to force a continuous 10g stream of fluid through a system, a part of which is heated by the burning of fuel into carbon monoxide, and a 'art of which is heated by the conversion o the carbon mon# oxide into carbon dioxide. It is estimated 11| tubes and water passages that per cent of the heating value of the fuel may be absorbed by the fluid.

Through thel gas-producer or preliminary water heater the slowly moving water preferably flows in a spiral pipe of relatively largle diameter, and a reserve body of this pre eated water may be accumulated in a drum. From this drum the water flows into headers, and from these'it passes through the secondary flame chamber in a set or grid of tubes of relatively small diameter, whereby it is split up, to be more intimately exposed to the heat. From the grid pipes the fluid is collected in headers which lead to a steam drumf. The primary water heating is effected by converting fuel into carbon monoxide, while the secondary heating of the same fluid to the point of' delivery as steam is effected by burning the carbon monoxide into carbon dioxide.

The air introduced into the secondary part of the furnace is heated by the hot gas from the rimary furnace, and by the heated walls of tie passage. This heated.. air is delivered right across the stream of carbon monoxidey gas passing from the gas-producer or rimary furnace to the flame chamber, tius causing amost intimate mixture of carbon monoxide and air. This mixture is `forced to take a zigzag path through the flalne chamber, and at every turn there is caused a morel intimate mixing, and opportunity is afforded for combustion to proceed properly to completion. All the gases are kept at ignition temperature by covering all water with heat-conducting material which is heated to the required high temperature by the flames. Thus all tubes and metal parts may be kept at an unfluctuating temperature, and there is not caused a great drop in temperature of' the hot gas directly it leaves the gas-producer.

The fluid tubes forming the grid in the flame chamber are preferably enclosed in jackets of non-metallic refractory plastic material, preferably heat-conducting, and may consist for example of a mixture of silicate of soda, asbestos, pumice and fireclay, although other non-fusible or refractory heat-conducting materials may be employed, as for example those which are commonly employed for radiating surfaces in gas-burning heaters for household use. These jackets may reach a condition of incandescence, and the flames contact with the jackets` but not with the water-containing pipes. Hence chilling and shortening of the flames` which would occur if the same were brought directly in contact with the waterpipes, is avoided, and av greater heating of the flowing water is effected. The interiors of the jackets, where they embrace the pipes, ma be cooler than the exteriors, but since th exteriors are incandescent the flames will be long drawn out, inasmuch as they contact only with surfaces which are about as hot as the dames, whereby additional economy of heat is attained. I

These grid tubes with their jackets may be packed closely together in the flame chamber in a manner to forni partitions, each of which may nearly close the flame chamber. The upward flame passages in alternate partitions may be at opposite ends, making the course of' the flames and gases zigzag.

The pre-heating tubes may be likewise enclosed in refractory heat-conducting jackets` the jackets taken together forming the walls of the gas-producer.

Ordinary boilers require a vigorous draught for producing high combustion; but by using the heat-retaining jackets, which whenincandescent do not quench the flames, it becomes practicable to provide for slow passage of the flames and gases through the grid in the flame chamber, there being preferably just enough draught through the top. of the flame chamber to draw the flames and gases through the generator, sothat before the gases escape they will have been deprived of as much heat as possible.

Obviously the extreme should be avoided 4 of pumping the fluid through the system atl such high speed that it will not abstract sufficient heat from the regenerating fur nace, and the opposite extreme should also be avoided of passing the fluid through the system so slowly that it will become heated to the desired degree long before it reaches the end of the system; but the fluid should be forced through at such a rate that it will absorb the maximum of heat just as it is about at the emerging point. It is a deL sideratum that as much heat as possible be abstracted from the burning coal in the gasproducer, and also that as much as possible be abstracted from the flames in the secondary heating or flame chamber. Therefore the heating is divided into two stages; in the first stage the water coursing through large pipes around the fire in the gas-producer, and in the second stage flowing in finely divided streams through the flames in the secondary chamber.

In order to adapt the generator for use where the demand for steam fluctuates, there is preferablyY incorporated between the first and second portions of the fluid-pipe system a drum to hold in reserve a large quantity of water which has been pre-heated by passing slowly around the gasprodueer- If therefore there is sudden consumption of a large volume of steam, the pre-heated Water from this drum will be supplied to the grid of final-heating tubes until the heat of the fire can be raised to a point to meet the demand for quickersteaming. Thus there is avoided the necessity of supplying relatively cool water to the grid. Provision is made for blowing out the gas passages to Clear them from soot and rit. Plugs may be removed from the fluid-pipes and headers to clean them from end toend, and the whole apparatus can be cleaned, including the big pipes around the gas-producer, without disorganizing the system.

Since the parts are small in proportion to the work accomplished, they stand the strain better than previous Igenerators. It is also noted that the generator does not require as careful watching to guard against collapse as do water-tube boilers, in which the water is iny relatively scantI supplyt Moreover, since the water keeps advancing, any steam bubble that might form would not stay long enoughgin one place to lead to undue heating of the tube.

Other features and advantages will hereinafter appear.

In the accompanying drawings, Figure 1 is a centralse'ctional elevation taken from front to rear on line l-l of Figure` 9, showing the gas-furnace or preheat'er at the front of the apparatus, and the secondary chamber and supper-heater atv the rear portion.

Figure 2 is a. plan of the apparatus, show-` ing also the pump which supplies to the steam generator a constant stream under `high pressure, say 300 pounds per square inch.

Figure 3 is a transverse sectional elevation taken at the line 3 3 of Figure l,

showing a unit or section of the super-'heabing grid, also the steam drum above the grid or secondary chamber, and a partial view of the water drum. 4Figure 3 shows a form of pressure-reduc ing val-ve between. the fluid heating system and the steam drum.

Figure 4 is a similar section taken on line 4-4 of Figure 1, showing the gaps formed by omitting alternate tubes in -one grid section, to afford vertical passages for the flames. 'Figure 5fis a front elevation, .partly in .,ection on line, 5-5 of Figure 9, and showing the gas-producer.

Figure 5 shows an enlarged cross-section of grid-tube and jacket.

Figure 6 is a diagram of the piping system and appurtenances.

Figure 7 is a part-sectional side elevation.

taken along line 7-7 of Figure 9, of a spiral tubular water-heating framework forming part of the gas-producer structure, and also a part-sectional side elevation of t-he superheating grid. A

Figure 8 is a rear elevation of the spiral tubular framework seen at Figure 7, and illustrating one length of tubeas omitted to form a flame gap. also the means of connecting adjoining lengths of tube; the seetion taken on line 8-8 of Figure 7.

Figure 9 is a part-sectional plan of the a primary heating pipe, which is illustrat` ed as forming a rectangular frame, Figures 7 and 8, through which the water flows up in a spiral course. Each of the long sides of` the frame is formed of a series of long tubes 23, and each short side of a series of short tubes 24, all' ot' said tubes being of relatively large diameter and inclined upwardly, and the tubes being connected by elbows 25 to forma 'spiral26. Preferably all the elbows at each corner ot' the spiral are cast in a singlepiece, Thus are formed four standards 27 at the corners. these standards taken with the tubes forming a framework .Y for the walls offthe gas-producer or pre- `regarded as comprising a tubular column which is divided into elbows by'means of horizontal closed partitions 28. The openings in the elbows are set at the same inclinations as the tubes, and each elbow is provided with a clean-out opening 30 so that access can be had to the tube from each end thereof; the clean-out openings' heilig closed by caps 31. This frame is open at the top for the introduction of fuel and air into the chamber, and is open at the bottom to set over a grate 82.

About midi Yay of the height of the traine, at the rear side thereof, one otithe`tubes`23 is omitted, this space bcing'left for t-lie egress of gases from the gas-producer or pre-heater. Accordingly, the two rear col# umns are left unprovided with openings for the ends of the omitted tube; or, in other words, the columns are boxed up at these points, as at 32. Between the left-hand elbowv at Figure 8 and the next.- elbow above., a passage is made, as at 33, forming an ofi"- set elbow, so that the flow of water up the spiral may not be interrupted. A similar opening is made at 34 between the elbows oi the corresponding pair in the right-hand column orv standard at Figure S, so that fiow may proceed through tubes 35, 36 and ,537. in which the water would otherwise be dead, these three tubes forming a. sort of bv- )ass or shunt. and enabling these middle' u P` .approved manner. lEach standard may be column may have the form of a pedestal 39,

there being ot' varying heights to accommodate the splral arrangement of tubes and elbows. Other forms of pre-heaters may be employed.y

' of a cross or From the upper end of' the pre-heater, the water rises through a short vertical pipe 40, connected by elbows or bent pipes 41, 42, preferably to the bottom of a reservoir or drum 43,. which fills with the pre-heated water. This drum may lie horizontally, rest-ing at its ends and middle upon bridges which span the top of the secondary or fiume chamber 44 of the regenerative furnace.

' The outlet 45 of the water drum is placed at the'top. It will be understood that if the outlet were at the bottom, it might happen that occasionally the drum ,would nearly fill with steam, only a small body of water occupying the bottom thereof; whereas it is desired to have the drum always filled, to constitute a reserve supply of heated water. Since the outlet is at the top, it will be seen that the pump must fill the drum with water before a supply can escape to the grid in the flame chamber.

. From the drum 43 the water flows through pipes, .including a pipe 46 which connects by an elbow 47 to a cross pipe 48, the latter having a. descending elbow 49 to the middle horizontal pipe 50, which at its ends is connected by elbows 51 to two horizontal distributing headers 52, 53, at opposite sidesdof the upper part of the flame chamber of the apparatus. In passing out of these headers, the water is s lit up or separated into numerous sma l independent streams, flowing simultaneously through small horizontal tubes 54, which may be arranged to form a grid. As seen at Figure 3,

these tubes may be of uniform length. It will be further observed at said fiffure that the two upper tubes are connected by a coupling or union 55 at their left-hand ends, and thatthe second and third tubes are connected by a similar union at their righthand ends, the third and 'fourth being connected at their left-hand ends, and so on to the bottom of the grid section, so that the stream of water takes a zigzag course from the top or intake to the bottom vor delivery end. The unions 55 at each end of the run oftubes, seen at Figure 3, may form a single upright casting 56, constituting a header, and having on its inner face perforations 57, in which the tubes are secured by expanding or otherwise, and having on its outer face clean-out openings 58 closed by conical screw plugs 59. The right-hand castingxat Figure 3 is provided at its upper end wit a conical nipple 60 which is fitted in a hole in the bottom of the header, and the castin also flanges 61 which are bolted to anges 62 has formed upon said header. At the bot-tom of Figure 3 are horizontal headers 63 and 64, the left-hand upright header 56 havingat its lower end a conical nipple 63 fitting in an opening in the left-hand bottom header 63, which has fianges 63b connected by short and long bolts to fianges 63c formed upon the bottom o the upright header. The ends of castings 56 have channels 56l connecting the tube sets with the headers.

The set of small tubes 54, seen at Figure 3, taken together with the upright headers 56 therefor form a section which is removable and attachable as a unit. By removing the bolts at the diagonally opposite corners thereof, the unit may be taken out from the apparatus, and cleaned or repaired, or replaced by-a new unit. The' two remaining corners of this unit or section preferably have supports 63, to rest against the upper and lower headers, as seen at Figure 3, these supports being threaded to permit adjustment.

These sections or units are placed side by side, Fioure 1, the first unit opening into one top header 52, the next unit'opening into the ot er top header 53, and so on alternately for the system of units; and the same plan is followed of opening alternately into the two bottom headers 63 and 64, by which the fluid, having received its final heating, is collected from the grid sections and eon ducted through a cross pipe 65 to an upright pipe 66 and elbows 67, 68, to the ends of a steam drum 69. This drum is supported upon the same bridges as the water drum, each bridge preferably comprising similar sections 70 placed end to end and joined by bolts 71, which connect the adjoining ends of the sections to a cross bridge'72 located between the drums; the outer ends of the sections being bolted to horizontal rails 73 forming part of the upper framework of the apparatus. In cachot' the elbow sections 67, 68, may be fixed a reducer 69, which may be in the form of a plug or partition having a small opening or nozzle 69", through which the fluid will discharge into the drum in the form of steam mixed with some water which rlatter may be afterwards converted into steam by the heat of the `furnace below. If two pressure-reducers 69l1 are used, each may lllb lll)

have an o enin of sa 5 of an inch' butf if only one is used, it may have an opening of say 1 inch.

The grid, or assembly of these units, is seen in cross-section at igure 1, and it will be observed that they are similar, except for the two outside units or sections at each side of the grid. The sections are .so assembled that for the main part the horizontal tubes 54 form tiers, one above another, these tiers or banks being formed into slabs or floors by the use of packing, as will presently be explained, these slabs being separated to allow the passage of flame. In orderl 4to make the desired zigzag flame passage, certain of the tubes are omitted from a section 74 near the front and from a section 75 near .the rear at Figure 1,50 that when the sections yare assembled, these omissions or gaps 75a'aliord space for the flames to turn corners in flowing back and forth up around the tiers of tubes. .The tiers (or slabs), as seen in Figure l, have aninterdigitated or fretwork eflect, each slab projecting within the Space between adjacent upper and lower slabs, but leaving at its inner edge an opening for the fla-mes. Section 75 is seen in sectional elevation at Figure 4,`where it may be compared with Figure 3. It will be seen lat Figure 4 that every other tube is omitted,

and that the coupling channel or unions 76 1n the upright headers al'e made correspondingly longer than the unions in headers 56. The course of the flame is indicated by the curved arrows at. Figure l. It will be understood that the section 74 corresponds with section 75 at Figure .4, except that it has a staggered relation thereto. In other 'wol-ds, there is an omission of only one tube nected to distributing header 53, and that the first horizontal tube (corresponding with 5,4) ln saidA section 74 1s opposite the top space 77 at Figure 4, and so on down, making a Azigzagcourse to the right-hand bottom header 64-y at Figure A4. The l extreme forward and rearward sections 78, 79, at Figure l, have the'tubes arranged about as seen in Figure 3. I the rear wall 80 ofthe flame chainber 44 are formed cleansout holes which are` filletl by removable plugs 8l opposite the ends of the horizontal portions of the zigzag passage. As will be seen at Figure l,

the front end of the grid is in the form of'a solid tube-encasing wall 78 of refractory heat-conducting material, while at the rear section of the grid is a similar construction,

no flame space being left in either of these walls, except the opening 78" near the bottom of the front wall for the ingress of air mixed with gas flowing from the gas-producer.

By means of the grid and its distributing headers, the flow of fluid is split'up into fine streams, so as to expose the fluid intimately to the flames, so as to heat it quickly, as it is intended to be keptcontinuously floW- ing. so that it will not remain'in the generator for many minutes, and will not absorb more heat than necessary to produce the required delivery ol steam, and shall not relexposure to the flames.-

Vtortuous course, to

ceive the last incrementbf such heat until the very momentthat it is about to reach the point for delivery into the steam drum.

Each of the horizontal tubes 54 at Figure 3 is provided with a jacket 82, preferably square in cross-section, as seen at Figure 1, and consisting of refractory material which may be heat-conducting and of a nature to become glowing or incandescent from Each of the grid sections, of which one is seen at Figure 3, has a heat-retaining lining 83 at its ends, consisting of refractory material, which may be similar to that of which the' jackets are made; and at the center of each section may be formed a vertical wall which, like the end lininvs, may have perforations for the passage of the tubes 54 therethrough. Said central support, which is also preferably of refractory material, may rest upon supporting bars 85 forming a portion of the framework. Each tube may have two jackets 82, one at each side of the central support 84. lThe jackets may pack together to form the slabs, walls, plates, shelvesor floors 86 which form the fretwork seen at Figure l, to compel the flames to pursue a prolong or augment the heating effect thereof. The lining walls, as well as the central walls or supports, may be built up of bricks or blocks, each having a perforation for the tube. Since each tube is fastened at both ends to the headers, it will be seen that the linings and jackets and central supports` are securely retained.

Each jacket 82 is preferably formed with 'a bore which is larger than the tube, the

or support 84,

difference' in diameter being about 11g of an inch; and in each jacket are formed at intervals internal flanges 87 which rest upon the tube, thus leaving a slight space 88 between the tube and the jacket. Thus the heat-conducting material need not necessa' rily be in close contact with the tube. It may be just out of contact With the tube from end to end, thus allowing yfull play for the greatest amount of heat to be radiated to the tubes, as well as for the jackets to absorb the heat from the flames. Each glowing jacket or heatconductor is very hot on thel exterior, but rela-tively cooler at its inner portion adjoining the tube. Since the outer surface of the jacket is at very high temperature, it radiates heat to other jackets. The jackets will absorb the heat from the flames and retain it, whereas if the llames had opportunity to play directly upon the water-tubes (which would not exceed the temperature of the water therein), the flame would be cooled and shortened or quenched. But the jackets are heat-absorbers, and' are refractory and do not Waste or dissipate the heat, and gradually rise to the temperature of the flame itself. It will also be understood that by avoiding the cooling or quenching of the flames, the liability of deposit of carbon upon the tubes or jackets is avoided, and hence the heating capacity of the jackets or tubes is maintained.

The grid tubing should be long enough to permit the flowing fluid to absorb sufficient eat to produce dry steam. rl`he fluid from the primary main enters the grid system at the top and is collected at the bottom, whence it is delivered from the generator. Thus the fluid enters the grid at the point Where the hot gases are coolest, and gradually passes down the grid through the flames to the point where the flames are hottest. A grid section having tubes of say,t of an inch diameter and about the proportions shown in the drawings, may be made to evaporate 700 pounds of water per hour. The grid shows sixteen sections or sets of tubing, but the invention is not limited to this particular number, as either more or less sections may be employed. Sixteen grid sections would evaporate 11,200 pounds per hour.

The system of tubing is of such a length compared toI its diameter that it will not only heat the water to a temperaure of steam, but it will also generate steam ,as dry as required. In practice, the pump works continuously, so as to force the highly heated fluid continuously out of the delivery end of the tubing system into the steam drum.

While the grid system preferably should not hold more than ten times the amount of Water to be evaporated each minute, still the primary main may hold more, but not so much as to cause waste by radiation, it being an aim to heat only what water is required for immediate use. 'l`he tubing system may be of a length that the water will eventually be completely evaporated to superheated steam of determined dryness. If the diam- 1 eter of the superheating tubes is 1 inch, the.

length of the system should preferably be not less than 326 inches, although a greater length ratio may be required as lowered temperatures are required or greater economy is reached.

By enclosing each small tube in a solid sleeve of heat-conducting material the objection of soot upon the tube is avoided, since none would form upon either tube or jacket; and an even temperature of the system is reached.

The large pre-heating tubes 23, 24 may be encased in jackets 89 of material similar to jackets 82; these bein preferably in the form of blocks, each b oek comprising two halves or sections 90, 91, having depressions fitting to opposite sides of adjoining tubes, the sections being held together by bolts 93; the inner end of each bolt being c0unter-sunlt in the block section, and the hole being lled by refractor material at 94. The floors and tops of the locks may be inclined to correspond with the directions of the tubes, as

seen in Figure 1, and the blocks may all fit together to form solid walls, as also seen in Figure l, so that flame will not lap the tubes and be uenched thereby, but so that the tubes will iave glowing coatings. Special blocks 95 may be fitted to malte the top of the furnace level, to receive its top plate 96; said blocks having inclined floors and being horizontal on their upper faces; and corresponding blocks 90 may be fitted to form the bottom of this gas-producing portion of the apparatus. lt will be observed that neither in the fuel furnace nor in the flame chamber does the flame come in contact with the relatively cool boiler tubes, but only in Contact with red hot or incandescent heat-conducting material.

Any suitable liquid or other fuel may be used in the gas-producer. In the form of the invention illustrated, provision is made for burning coal, coke or other solid combustible. The coal may be fed through a hopper 97 and chute 97lL at the top of the furnace and rest upon grate 32, and may fill the chamber as far as'desired. A forced draught of airis provided by a blower or device 98, which supplies air through pipe 99 to an air-'boit 100 extending around the ashpit 101, air entering below the grate through perforations 102 in the wall of the air-box. Air may also be `forced into the top of the furnace through branch 102 when coke is the fuel. The air may be supplied in such proportion that combustion proceeds to the point of producing carbon monoxide, which passes, as indicated by the arrows. through a passage 103 in the rear ot' the g s-producer, and then downwardly throng" a vertical passage 104 to the bottom portion of the seeondary heater or flame chamber 44. 'lhe gases passing from the pre-heating portion or gas-producer to the secondary or final heating portion 114 ot' the apparatus consist' largely of carbon monoxide, but this is kept at ignition temperature, and a spontaneous secondary ignition or burning of the gases to produce carbon dioxide is induced by the introduction of a heated sheet of fresh air under pressure fronrsaid blower 98. Said fresh supply comes down from blower 98 through a pipe 105*L and vertical passage 105 in a middle wall 10G of the apparatus, and mixes intimately with thel product of the gas-producer. 'l`he flames circulate in a zigzag path from the bottom to the top of the secondary heater, as indicated by the arrows, Figure 1, and the waste gas escapes` through relatively constricted passages, which may be formed by omitting the jackets alternately from say three of the hori zontal tubes 54 in the upper tier, as shown at Figure 1. The hot gas escapes into thel chamber 107 which contains the water und steam drums, and circulates around these diums on the way to the chimney 108. This by say 10 percent the heat of the water and steam within the drums, and tend to superheat the same, or at least compensate for i loss of heat therefrom, if any; the gas'pref-.

erably passing both `between and around the drums. i

Thus theheatingmay be effected or expeflited by combustion in thejpriinary part of a regenerative furnace, through heat conductors of refractory material, which may be '15 of the described material, or in some cases of brick or vcast iron; by heat from 'secondary combustion through refractory. material in which the small tubes are placed; by the heat of waste gas fiowingvoutaround the steam and water drums; by the counter-flow of water from the relatively cool region where the n gas escapes, to the region where thel flames are generated in the secondary furnace, where the heat is greatest; by keeping the 2a gas at ignitiontemperature, and by not allowing it to come into contact with tubes or metal parts containing water, until it escapes around the steam and water drums; by causing the exact amount of air required 3o for combustion to 4be fed to the secondary combustion chamber;y by employing a sort of catalytic transmission of heat from a conducto;` which is kept inglowing condition to rthe water which is heatedby the radiation;

3., and by giving the final heating ina secondary system which oes not contain more than about ten time the amount of fluid to be evaporated per minute.

ltwill be seenthat a maximum evapora- 40 tion of water for fuel consumed may be secured by having in the secondary system not more than, ten times the .quantity of fluid evaporated per minute completely surrounded b the flames; by having a continuous flow of fluid in a direction contrary .to

the path taken by the flames, so that the hottest part of Athe fiames is at or near the point of of the Huid from the system; by

heating byl radiation, which is rendered possible by having heat conductors of a nature to absorb heat units to the point of saturation; each individual conductor re-acting upon the adjoining conductors until the temperature of iall the conductors is brought to Y n i s n .55 the maximum; by having these foregolng 4elements abstract and retain the maximum heat units and re-act upon one another with the proper quantity 'of flowing Huid subjected to heat at vall stages of its single di- .n rection flow through a suitable system of The cost of producing and maintaining a pressure of 300 pounds per square inch, is but little more than wouldbe the cost for a pressure'of 65 pounds; and the present invention produces this high pressure economically, by

-usingthe two-stage combustion and having radiant Vheat retainers to t'ansmit the heat to the pipes .without liability. of quenching the flames.

Since the flame temperature of carbon monoxide is 38000, it is apparent that there isa great loss in even the most modern boilers,especially when it is taken into consideration that at higher temperatures than 2000CJ F. more carbon monoxide is formed than carbon dioxide, even-if a surplus of air is forced through the fire. Thus it will -be seen that results sought by forcing ordinary boiler tires to white heat are'far less than obtained bythe-use of the regenerative fur-- nace feature of the present invention.

In a Stimm-generator made 'substantially according to the draw-ings and of a size 7 feet' 9 inches by 7 feet 6 inehesby 0 feet G inches, using as fuel one inch cubes of coke, of 13,000 to 14,000 British thermal units per polimi, the estimated combustion would be S00 pounds. for 'moderate steaming, and 1200 pounds for full power per hour. The evapo-` Arat'on for moderate steaming would be 8000 pounds of water. per hour and for full power would be 12,000 pounds per hour; water being fed into the generator at 7 6 F. This estimated performance may be compared with that of a standard boiler ot" Sterling type, which, in order to evaporate 12,000 pounds of water per hour, would have to be, width 1.0 feet' (i inches, length back'to front 22 feet 3 inches and height from floor to center of valve outlet 20 feet 10 inches, weight about 20 tons, not including the furnace fittings.

According to the usual practice, say 10 tous of water would he boiling and circulating in a boiler and l ton per hour would be evaporated, of this one evaporated ton only half would usually be used. Since the stealn is in contact with a body o f water whose temperature is at. the boiling point, the. steam necessarily condenses, whereby is incurred a dead loss. Moreover, this condensed steam has to be reevaporated, and this causes a further loss. These losses are reduced or overcome by the present generator, which moreover may in some cases use water which.

is unfit for ordinary steam-boilers, for eX- ample salt Water, since it is in constant flow through the piping, keeping it clean.

Below the monoxide passage is formed in the center a sump for asheswhich may be closed by doors 111. Two fire doors 112 may be provided, just above the grate, and two doors 113 opening to the ash-pit.

lVhen a supply of steam is no longer desired, a by-pa`ss is brought into use .iu the preheating system,- throngh which the water may flow slowly. A valve 114, Figure 9, which is normally closed, in a pipe 114, between the intake endv of the pre-heating system and the vater-drum 43, is opened, so.

Ful

that the Water may rise in the spiral and then pass through the water-drum, yand through the pipes and back to the intake sideiagain. Thus 4conservation of fuel is effected, and the apparatus may be maintained for a long tiine'with the water in heated conditionjwithoutundue expense for fuel, so that the apparatus is ready for quick steaming whenever desired.

i .Other fuel may be employed, such as oil,

Lor coal tar, and iu suoli case the furnace ,would be at least half filled with heat-conducting slabs of refractory material arranged to radiate heat to the furnace walls enclosing the water-main tubes; sufficient air beinnr admitted to form carbon monoxide, to which is introduced at the secondary stage heated aii to form carbon dioxide, as when coal is consumed. Charcoal may be used for fuel, or non-coking brown coal, or other fuels.

Simultaneously with the opening of valve '114 theie is preferably closed a` valve 115, Figure 2, which cuts oil' the grid and the steam drum while no steam is being generated or while the furnace is being started. Valves 114 and 115 may be connected in any suitable Way so that as either is closed the other opens. The valves may be connected by a train of gearing, comprising pinions 116, 117, shaft 118, and pinions 119, 120; a hand wheel 121 being provided for closing either valve and simultaneously opening the other. While' valve 115 is closed, water circulates slowly through the spiral and the water drum, and if desiredl the blower may be stopped, and fuel economized. The water drum may have asafety valve 122 set to say 300 pounds pressure, as it is intended to nia'ntain this 'high pressure of the water in order to give it a great heat-absorbing capacity.` f l ln starting the furnace, the valve 115 is closed and 114 is opened. Wood and coal f are placed upon the grate, and while the coal is"igniting the Water heats in the primary system and in the water drum, circulation continuing until the Water is above boiling temperature. The pump at this time is idle. This heating containues until the fires begin t0 make it evident that gas will burn in the secondary chamber. The damper in the chimney is then opened, and air is admitted through the lue to the stream of hot as passing into the secondary chamber.4 'ghe valve 115 may be gradually opened (valve 114 closing), and the pump started. The grid will gradually be forced full of heated Huid, which will become supe'rheated by the Haines inthe secondary chamber.

While starting the furnace, a by-pass coniprising pipes 99 and 123 may be employed' by opening a damper 124 therein; said bypass pipe 123 extending from the top ofthe gas-furnace to the alain chimney 108 above draw the water, as shown diagramimitically',

at Figure 6.

A variety of pressure-reducers may be employed. For example, at Figure 3 the pressure-reducing opening 69" in the plug (19 is gradually enlarged as it approaches the steam drum G9; this arrangement being the reverse of that seen at Figure 9, in which the small opening 6'9" is at the inner end of the reducing or choking device 69a which thus has the form of a tapering nozzle or jet with its small discharge end pointed into the steam drum. At Figure 3, a weighted valve 125 has a seat 126 in a fitting 127 at the top of one or both of the pipes 66. This valve can slide up and down in a chamber 12T. 4A pipe 128 leads from said chamber to the elbow (i8 communicating with the steam drum 69. Valve 125 normally closes pipe 128; but when pressure rises in pipe 66,' the valve lifts, opening communication between 66 and 128; thc pressure above 125 being somewhat increased by the fluid escaping thi-oughfrom 66 to 128 and 127, so that there is no undue expansion of fluid through the valve. This form may take the place of the reducers seen at Figures 3 and 9.

The apparatus may be provided with heatretaining side walls 129, and a front wall 130.

Variations may be resorted to within the scope of the invention, and portions of the improvements may be used without others. For example, the secondary air passage may be omitted and the entire apparatus may be heated directly in the manner of an ordinary furnace, having nov secondary coin bastion. The apparatus, moreover, may be used in other ways.

Having thus described my invention, I claim:

1. The combination of a pump, a system of continuous high pressure fluid piping through which the fluid is forced only once by the pump, and means to heat the piping sufiiciently to heat the fluid above the boiling point, pressure maintaining means being provided at the delivery end of the system to restrain the heated fluid against undue speed of discharge; said heating means comprisingr a prelieating furnace surrounded by a coil of said piping of relatively large diameter and into which the Htl liu) 

